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What is the ISDN Switch Off?

Rotary phone | IDSN Switch off

With 2019 well underway, we’re another step closer to the planned ISDN switch off, scheduled in for 2025.

We’re a little way off yet, but understanding the ISDN switch off is important if you’re making decisions around your business telephony infrastructure in the near future.

Understanding PSTN and ISDN

You’ll hear PSTN and ISDN commonly used in this type of discussion. For clarity, PSTN stands for Public Switched Telephone Network and refers to the copper wire system that has been helping us make phone calls since the 1800s. It’s a physical infrastructure - think of the ‘landline’ you likely grew up with.

ISDN stands for Integrated Services Digital Network - the integrated part of the phrase referring to the ability to deliver multiple types of connections over one line.

This technology became popular when communication options like voice, data, fax and early video were gaining ground.

The End of an Era?

The UK’s PSTN physical network is owned and maintained by BT, who established it in 1986.

However, in 2015, BT Openreach announced that they would be phasing out the current PSTN and ISDN networks by 2025.

As communication has become more digital the need for PSTN has naturally diminished. No longer do we need to check if anyone in our household is on the phone before we change our connection to access the internet - remember that pain?

With more businesses had been making the switch to IP (internet based) services, the running and maintenance costs for PSTN and ISDN can be hard to justify.


Internet telephony, e.g. VoIP or Voice Over Internet Protocol, has gained popularity due to its affordability and ease of set-up and maintenance, with reduced need for on-site equipment.

The reliance on an internet rather than a physical connection also allows for increased freedom and flexibility.

However, with an estimated two million businesses still operating their telephony over ISDN, this explains the large period of advance notice on the service withdrawal.

Business freedom with cloud communications

Beyond Cost to Real Growth

For us, the ISDN switch off marks an exciting new phase for business telecoms, rather than a doomsday blackout or even the death of the desk phone.

We’re bringing together the latest technologies to help our customers go beyond cost savings to real growth.

Our cloud solutions are helping our customers benefit from greater productivity, more control over spend and empower a mobilised workforce - plus more.


Get inspired by the potential of cloud communications for speed and flexibility



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